Flying operations for the U.S. Navy's Lockheed Martin F-35C Joint Strike Fighter (JSF) test program resumed June 23 after a six-day suspension to fix a software problem.

The aircraft were grounded June 17 when engineers at Patuxent River Naval Air Station, Md., discovered a "logic fault" that could have prevented the proper action of aircraft control surfaces - the flaps, rudders and other movable elements that maneuver the plane through the air.

The software problem affected the "safety mechanism that ensures the wings are folded properly," said Lt. Courtney Hillson, a Navy spokesperson at the Pentagon. "It's the mechanism that prevents the flaps from moving in flight."

The Navy stressed that no actual fault took place on any aircraft in the air or on the ground.

The safety monitoring function for the folding mechanism should be turned off during flight, Hillson said, but the software was not properly turning off the function.

The problem has yet to be fully corrected, but the aircraft have resumed flying with certain restrictions, according to a statement from Naval Air Systems Command (NAVAIR) at Pax River.

"A software fix is in progress, and the team has structured temporary maneuvering limitations to ensure it is not a safety hazard," NAVAIR said in the statement.

"Finding issues such as this is the purpose of aircraft test and evaluation," Hillson said. "By finding and correcting such issues, the test team is delivering a better product to the fleet."

The first of three F-35Cs in the Navy flight test program began operating from the Pax River test center in November. The C model differs from the A model for the Air Force and the short-takeoff-and-vertical-landing B version for the Marine Corps in that it has folding wings for storage aboard an aircraft carrier.

The Navy JSF team "is still on track to commence initial carrier suitability testing next week with jet blast deflector testing in Lakehurst, N.J.," NAVAIR said June 24 in its statement.

The deflector tests at the Navy's carrier aviation test facility in Lakehurst will be followed in late July or early August by catapult launch and arrested recovery tests, Hillson said.